Field of the Invention
The invention relates to a method for enabling a vehicle to influence a traffic light signal system equipped with an evaluation computer, in particular in public transportation, wherein the vehicle at a sending position sends a data telegram to the evaluation computer to request a green phase, and wherein the data telegram and/or the transmission position depend on predefined reporting points.
In addition, the invention relates to an evaluation computer for influencing a traffic light signal system for performing the method according to the invention.
Finally, the invention relates to an on-board computer for a vehicle for influencing a traffic light signal system for performing the method according to the invention.
Description of Related Art
Methods and systems for influencing traffic light signal systems of the type defined in the introduction are known from practice in a wide variety of embodiments. The known systems make it possible to influence traffic light signal systems to optimize the driving times of vehicles. The traffic light signal system is influenced via data radio. To do so, a suitably equipped vehicle sends data telegrams to the traffic light signal systems via data radio on reaching reporting points. A certain data telegram is assigned to each reporting point here. The position of the vehicle is determined physically in the access area to the traffic light signal system by location synchronization. Depending on the local conditions, data telegrams are sent from the vehicle to the traffic light signal system, different data telegrams are sent from the vehicle to the traffic light signal system for influencing the traffic light signal system:
Advance log-on telegram: The vehicle is near the intersection, where the traffic light signal system is located. It will soon need a green phase.
Main log-on telegram: The vehicle is right at the intersection and needs a green phase now.
Station telegram: This data telegram is used when a station is located just in front of the traffic light signal system. The data telegram informs the traffic light signal system that the vehicle is ready to depart as soon as the doors of the vehicle are closed.
Log-out telegram: The vehicle has passed the intersection. The green time can now be terminated.
The data telegrams that are sent are received, decoded and processed by an evaluation unit assigned to the traffic light signal system. Next the processed data is made available to the control unit for control of the traffic light signal system. The intervention into the control unit results from this. The control unit processes all the information contained in the data telegram, such as the reporting point number, schedule deviation and a priority code.
One of the most important requirements and boundary conditions in influencing traffic light signal systems is that the transmission time of the data telegrams and/or the position (reporting points) at which the data telegrams are sent must be upheld very precisely. The log-out point, i.e., the position and/or time after which the intersection may be released again for normal traffic is especially critical. The vehicle should not send the log-out message too soon, so as not to cause it to switch to red at the last moment, but should also not send it too late if it has already left the intersection area. The vehicle should send the log-out message exactly at the planned departure point and should then release the intersection again.
The known influencing systems for traffic light signal systems use the analog radio telephone system with 4 m, 2 m or 70 cm frequency band. Depending on the requirements in the given application case, different types of data telegrams are used, also having different lengths:
TelegramDuration with upType ofNumber ofNumberdurationand switch timestelegrambytesof bits[ms][ms]R09.103602550R09.1146929R09.1257833. . .. . .. . .. . .R09.169114 4880
From the above table, it can be seen that the simple transmission time in the radio network requires less than 100 ms. These systems are characterized in that a direct real time connection between the requesting vehicle and the stationary receiver side—traffic light signal system at the intersection—can be established (direct mode operation, DMO). The data telegrams are sent spontaneously by the vehicle on reaching a certain position. The known methods have the disadvantage that it is a unidirectional communication, i.e., only the vehicle sends a message and there is no acknowledgement on the part of the traffic light signal system. Furthermore, there is a collision of radio data telegrams when several vehicles send a request at the same time. Consequently, the transmission is not confirmed. To reduce these disadvantages, data telegrams today are repeated once or twice in an interval of time controlled by a random generator. Typical values here are in the range of 200 to 800 ms. Starting from a vehicle speed of 36 km/h (1 m per 100 ms), the lack of precision caused by the radio system is in the range of 1 m to max. 10 m.
In addition, today there are more and more systems in short-range public transportation which rely on an IP-based digital wireless infrastructure, such as GPRS or UMTS, for example, for data communication between vehicle and control station. Nevertheless, approaches based on the analog radio telephone system are still being used to influence traffic light signal systems today but these would then require special equipment—data telegram transmitters—in the vehicle. It is thus a special disadvantage of systems which use the radio telephone that separate vehicle equipment is needed to use this system and separate frequencies are needed for the radio telephone.
The object of the present invention is therefore to provide and improve upon a method, an evaluation computer and an on-board computer for enabling a vehicle to influence a traffic light signal system, such that a prompt influence on the traffic light signal system is ensured by using simple design means.